Electric switch



P. H. CHASE.

ELECTRIC SWITCH.

APPLICATION FILED JUN; 23. 1919.

Patented Mar. 7, 1922.

2 SHEETS-SHEET l.

AYQAWGJV O 0 O O BZ HINgEkTOR P. H. CHASE.

ELECTRIC SWITCH. APPLICATION FILED JUNE23, I919.

Patented Mar. 7, 1922.

2 $HEETSSHEET Z.

INVENTOR NEY UNITED STATES PATENT OFFICE.

PHILIP H. CHASE, OF CYNWYD, PENNSYLVANIA, ASSIGNOR TO SEARS B. CONDIT,OF BROOKLINE, MASSACHUSETTS.

ELECTRIC SWITCH.

Application filed June 23,

To all whom. it may concern:

Be it known that I, PHILIP H. CHASE, a citizen of the United States, anda resident of Cynwyd, in the county of Montgomery and State ofPennsylvania, have invented an Improvement in Electric Switches, ofwhich the following is a specification.

Certain features of this invention are disclosed in copendingapplications of George A. Burnham, Serial No. 354,920, filed Jan. 29,1920, and a divisional application thereof, Serial No. 420,513, filedOct. 29, 1920, which applications are assigned to Sears B. Condit.

This invention relates to electric switches,

and with regard to certain more specific fea tures, to a device for usein connection with oil switches, or oil circuit-breakers.

Among the objects of the invention may be noted the provision of asimple and ef fective device for increasing the strength of the switch,particularly its resistance to the shocks accompanying the flow of heavycurrents such as those incident to short circuits; the provision of anexpansion chamher for absorbing part of the fluid pressure occasioned bygases and the heating or volatilizing of oil at the arcs, when thecircuit is being broken; the provision of a tank, shell or casing soconstructedas to minimize the tendency of the casing to burst under theinfluence of excessive pressure thus occasioned; and the provision offeatures conducive to safe and eflicient operation of the switch.

Other objects will be in part obvious and .in part pointed outhereinafter.

The invention accordingly consists in the features of construction,combinations of elements and arrangement of parts which will beexemplified inthe construction hereinafter set forth, and the scope ofthe application of which will be indicated in the following claims.

In the drawings, in which is illustrated one of various possibleembodiments of the invention,

Fig. 1 is a vertical section of a preferred type of switch;

Fig. 2 is a top view of Fig. 1; Fig. 3 is a vertical section on the line33,

Fig 2;

ig. 4 is a horizontal section on the hue 4-4, Fig. 1;

Fig. 5 is a vertical section on the line 5-5, Fig. 6, showing amodification;

Specification of Letters Patent.

Patented Mar. *7, 1922.

1919. Serial No. 306,098.

Fig. 6 is a vertical section of said modification;

Fig. 7 is a horizontal section on the line 7-7, Fig. 8, showing a secondmodification;

Fig. 8 is a vertical section of said second modification.

Similar reference characters indicate corresponding parts throughout theseveral views of the drawings.

Referring now more particularly to Figs. 1 to 4 of the drawings, thereis illustrated a single-pole electric switch, of the type knowncommercially as an oil switch, comprising a casing 1, in the upperportion of which are mounted tw'o insulating bushings 3, a for theterminals 6, 7, connected respectively to the fixed contacts 9, 10Mounted centrally in the casing for vertical movement with respectthereto, is the operating rod 12 carrying the conducting yoke 14 ateither end of which are mounted the movable contacts l6, 17, here shownas provided with arcing tips. When the rod is moved to its upperposition by suitable operating means, the circuit across the two fixedcontacts is closed. hen the rod is moved 1 downwardly, this circuit isopened. At the moment of downward motion, from the time the contactsbegin to separate, an arc is formed between each fixed contact and itscorresponding movable contact if there is any current passing throughthe circuit at the time. Under ordinary conditions these arcs areextinguished by the oil, which ordinarily fills the tank up to about thenormal level 19. When the current is above normal values. however, asoccurs, for example, when abnormal conditions prevail in the externalcircuit, the oil does not readily extinguish the arcs, and in manyinstances the heat generated by the arcs is great enough to volatilizethe oil, and generate pressure that forces the oil out of the easing, ifthere is opportunity for it to do so, or even to break or burst thecasing.

In order to overcome these disadvantages, the present invention providesseveral features of construction which in many instances may be utilizedseparately or in various combinations with one another.

One of these features is the provision of an auxiliary expansion chamber21 shown in this instance in the upper part of the casing, preferablyseparate from the main expansion chamber 23 but communicating with theoil at or near the bottom of the tank circuit cause the pressure of theoil in the lower part of the chamber to rise above normal, the oil isthus free to travel upwardly through the annular passage 25 into theauxiliary expansion chamber 21, the pressurein the latter being relievedif desired by a baflied outlet 29 (Figs. 1 and 2), shown more in detailin Fig. 3. This may be similar in construction to the baflled outlet 31connecting the main expansion chamber 23 with the external atmosphere.The outlets are preferably baflled, in order to decrease the liabilityof loss of oil through the outlets when the pressure within the casingforces air and other gases out.

The inner wall 27, as indicated in Fig. 1, is broken away at a pointabove the bottom of the tank, to permit flow of oil from the inner partof the tank outwardly into the annular passage 25. The heat generated bythe arcs causes pressure to be exerted upon the oil below the arcs aswell as above the 'arcs, and this auxiliary expansion chamber isparticularly effective in relieving the pressure below the arcs, thatis, the pressure exerted downwardly. The main expansion chamber takescare of the pressure and movement of oil and gases in an upwarddirection, that is, above the arcs.

1n orderto further relieve the tank of the excessive mechanical shocksoccasioned by the generation of abnormal pressure, this inventionprovides a tank'bottom 33 (Figs. 5 and 6) of curved shape, with itshighest point or apex 34 substantially in line with the operating rod 12or midway between the contacts 9, 16 and 10, 17. The tank then slopesdownwardly away from this apex in either direction, and then slopespreferably upwardly as it approaches the side wall 35 of the casing, asindicated in Figs. 5 and 6. With this construction the downward pressureand flow of oil is directed or reflected outwardly and upwardly, whereaswith a flat bottom there is greater tendency for the oil to blow thebottom out of the tank when abnormal volatilization and pressure occursat the arcs.

\Vith the inner-wall and auxiliary expansion chamber construction abovedescribed, this deflecting bottom assists in directing the oil upwardlythrough the annular passage 25. If these features of inner wall andauxiliary expansion chamber are omitted, the deflecting bottom is'stilluseful in lessening the tendency of the bottom to be blown outward; insuch case the deflecting construction increases the circulation of oilupwardly along the outer wall of the easing and thus relieves thepressure at thebottom, the oil passing upwardly into the singleexpansion chamber; whereas if an auxiliary expansion chamber isprovided, the oil passes into the latter.

The side wall may be provided with a reinforcing and deflecting plate37, shown in Figs. 7 and 8. This plate serves to strengthen the sidewall of the casing, and also to direct outwardly moving fluid into adownward and upward direction. The apex 39 of the plate is preferablyadjacent the arcs, as is indicated in Fig. 8.

While a single-pole switch is illustrated herein, the invention isobviously applicable to multiple-pole switches.

Means for operating the switch through the rod 12 is not shown, as itforms per se no feature of the present invention. Such means may bemanual or mechanical.

1 My invention is obviously not limited to the embodiments hereindescribed and illustrated.

I claim:

1. An electric switch combining relatively movable contacts, a casing inwhich said contacts are mounted, an insulating fluid in the casing, theSurface of said fluid being normally at a single level, andfluidpressure-relieving means adapted to direct fluid moving downwardlyin the easing into an outward direction, said means comprising a curveddeflecting surface against which the downwardly moving fluid strikes,and by which said fluid is directed into an outward direction 2. Anelectric switch combining relatively movablecontacts, a casing in whichsaid contacts are mounted, an insulating fluid in the casing, and acurved bottom for the casing adapted to direct downwardly moving fluidinto an outward direction and thence into an upward direction.

3. An electric switch combining fixed contacts, mOXHblB contactscooperating therewith, a casing in which said contacts are mounted, aninsulating fluid in said casing,

an expansion chamber above the fluid level,

an auxiliary expansion chamber, and means adapted, upon the formation ofan arc at the contacts, to direct fluid away from the contacts andtoward said auxiliary expansion chamber.

4t. An electric switch combining relatively movable contacts, a casingin which said contacts are mounted, an insulating fluid in the casing, acover for the casing, an inner wall between the contacts and the casing,a cover extending across the top of said inner wall to enclose the spacewithin said inner wall and form a main expansion chamber therein, thespace above the fluid level and outside said cover and within the coverof the casing forming an auxiliary expansion chamber.

5. An electric switch combining a casing an inner wall therein, contactsmounted within said inner wall, and an insulating ana-sec fluid in thecasing and normally under mospheric pressure, the space outside saidinner wail and above the fluid level therein forming an expansionchamber.

6. An electric switch combining casing, an inner wall therein,relatively movable contacts within said inner wall and insulatedtherefrom, an insulating fluid in the casing and normally at a singlelevel, the space above the fluid level and outside said inner wall andwithin the cover of the casing forming an expansion chamber.

7. An electric switch combining acasing, and relatively movable contactstherein mersed in an insulating fluid, the casing having a portionprojecting inwardly toward said contacts to direct away from thecontacts the fluid forced against said portion when an arc is formed atthe contacts.

8. An electric switch combining a casing, and relatively movablecontacts therein immersed in an insulating fluid, the casing having aninner wall rovided with a portion projecting inwar ly toward saidcontacts to direct away from the contacts the fluid forced against saidportion when an arc is formed at the contacts.

9. An electric switch combining relatively movable contacts, a coveredcasing in which said contacts are mounted, an insulating fluid in thecasing, and a perforated inner wall between the contacts and the casing,the space above the fluid level and outside said inner wall nd withinthe cover of the casing forming an. expansion chamber, the fluid that isdirected downwardly upon the formation of arcs at the contacts passingupwardly through the passage between inner wall and casing and into saidexpansion chamber..

10. An electric swiitch combining relativel mova'ble contacts, a coveredcasing in whic said contacts are mounted, an insulating fluid in thecasing, a curved bottom for the casing adapted to direct downwardlymoving fluid into an outward direction, an inner wall between thecontacts and the casing, a cover extending across the top of said innerwall to enclose the space heneath said inner wall and forming a mainexpansion chamber therein, the space above the fluid ievel and outsidesaid cover and within the cover of the casing forming an auxiliaryexpansion chamber, the fluid directed downwardly upon the formation ofarcs at the contacts passing upwardly through the passage between innerwall and casing and into said auxiliary expansion chamber.

11. An electric switch combining a pair of fixed contacts, a pair ofmovable contacts cooperating therewith, a casing in which said contactsare mounted, oil in the casing, an expansion chamber in said casing, adeflecting bottom for the casing adapted to direct downwardly moving oilinto an outward direction and thence into an upward direction, an innerwall extending around the casing between the contacts and the casing andhaving a portion extending toward the arcs to direct u wardly anddownwardly the fluid flowing i rom said arcs toward said inner wall, acover extending across the top of said inner wall to enclose the spacebeneath said inner wall and forming said expansion chamber therein, thespace above the oil level and outside said cover and within the cover ofthe casing forming an auxiliary expansion chamber, the oil directeddownwardly upon the formation of arcs at the contacts passing upwardlythrough the annularpassage between inner and outer walls and into saidauxiliary expansion chamber, and outlets permittin passage of airbetween said chambers and atmosphere.

12. An electric switch combining a casing, an expansion chamber therein,relatively movable contacts within said chamber, an insulating fluid inwhich said contacts are immersed, a second expansion chamber in saidcasing, communicating with the first chamber, and automaticallyrepeatedly operative means operable independently of movement of saidcontacts, for directing fluid from the first chamber to the secondchamber to rclieveany abnormal fluid pres sure in the first chamber.

In testimony whereof, I have signed my name to this specification this21st day of June, 1919.

PHILIP CHASE.

